Wireless communication networks have become increasingly prevalent over the past decade. In recent years, a type of mobile communication network known as an “ad-hoc” network has been developed. In this type of network, a mobile node is capable of operating as a base station or router for other mobile nodes without using fixed infrastructure base stations. More sophisticated ad-hoc networks are also being developed which, in addition to enabling mobile nodes to communicate with each other as in conventional ad-hoc networks, further enable the mobile nodes to access a fixed network and thus communicate with other mobile nodes, such as those of a switched telephone network (PSTN), and on other networks such as the Internet. The mobile nodes of such networks may assume any number of random positions within the network, making exact node location determinations difficult when needed. For computing node geographical coordinates in such ad-hoc wireless networks, algorithms in use at individual nodes in typical networks use a “Time of Arrival” (TOA) measurement technique.
A Time of Arrival (TOA) measurement provides the distance between mobile nodes for computing a mobile node position. The measurements are based upon signal propagation times, specifically the time a signal needs for traveling between transceivers of a target node and a reference node. Historically, TOA measurements provide an estimate of the distance between two transceivers, or nodes, using approaches that assume that any information received is via a direct path channel. Existing TOA measurement methods detect a peak of a correlation function of a received signal. This peak, however, could be the manifestation of the direct path only or the direct path “tainted” with delay spread. TOA measurements can thus be inaccurate due to delay spread and multipath in the communication channel. Furthermore, existing methods typically average TOA measurements to determine distance which can lead to a trade off between convergence and accuracy.
Accordingly, it would be beneficial to have an improved method of determining the distance between nodes of a wireless communications network that would address the delay spread and multipath problem.